Papers by Author: Jim Metson

Abstract: The widely used Si3N4-SiC sidewall refractories for aluminum smelting cells, and β SiAlON-SiC composites that can be potentially used for this purpose, have been produced by reaction bonding and their corrosion performance assessed in simulated aluminum electrochemical cell conditions. The formation of the Si3N4 and SiAlON phases were studied by reaction bonding of silicon powders in a nitrogen atmosphere at low temperatures to promote the formation of silicon nitride, followed by a higher heating step to produce β SiAlON composites of different composition. The corrosion performance was studied in a laboratory scale aluminum electrolysis cell where samples were exposed to both liquid attack from molten salt bath and corrosive gas attack. The corrosion resistance of the samples was shown to be dependent on the composition but more importantly on the environment during corrosion, with samples in the gas phase showing higher corrosion.

Abstract: The surface characteristics of an extruded 6060 aluminium alloy were investigated with X-ray Photoelectron Spectroscopy (XPS). The results revealed that the extruded surface was covered by oxides of aluminium and magnesium. The thickness of aluminium oxide was found to change along the extrusion direction with the thinnest and thickest oxide at the beginning and end of the extrudate, respectively. Magnesium segregation was found on the surface of the extrusion with the highest and lowest Mg concentration at the beginning and end of the extrudate, respectively. This is the inverse result of that expected where increasing Mg content was believed to be associated with film instability and thicker films.